Class: Teacup::Stylesheet

Inherits:
Object
  • Object
show all
Includes:
StylesheetExtension
Defined in:
lib/teacup/stylesheet.rb

Overview

Stylesheets in Teacup act as a central configuration mechanism, they have two aims:

  1. Allow you to store “Details” away from the main body of your code. (controllers shouldn’t have to be filled with style rules)

  2. Allow you to easily re-use configuration in many places.

The API really provides only two methods, #style to store properties on the Stylesheet; and #query to get them out again:

In addition to this, two separate mechanisms are provided for sharing configuration within stylesheets.

Firstly, if you set the ‘:extends’ property for a given stylename, then on lookup the Stylesheet will merge the properties for the ‘:extends’ stylename into the return value. Conflicts are resolved so that properties with the original stylename are resolved in its favour.

Secondly, you can import Stylesheets into each other, in exactly the same way as you can include Modules into each other in Ruby. This allows you to share rules between Stylesheets.

As you’d expect, conflicts are resolved so that the Stylesheet on which you call query has the highest precedence.

The two merging mechanisms are considered independently, so you can override a property both in a ‘:extends’ rule, and also in an imported Stylesheet. In such a a case the Stylesheet inclusion conflicts are resolved independently; and then in a second phase, the ‘:extends’ chain is flattened.

Examples:

stylesheet = Teacup::Stylesheet.new
stylesheet.style :buttons, :corners => :rounded
# => nil
stylesheet.query :buttons
# => {:corners => :rounded}
Teacup::Stylesheet.new(:ipad) do
  style :button,
    backgroundImage: UIImage.imageNamed("big_red_shiny_button"),
    top: 100

  style :ok_button, extends: :button,
    title: "OK!",
    top: 200

end
Teacup::Stylesheet[:ipad].query(:ok_button)
# => {backgroundImage: UIImage.imageNamed("big_red_shiny_button"), top: 200, title: "OK!"}
Teacup::Stylesheet.new(:ipad) do
  style :ok_button,
    title: "OK!"
end

Teacup::Stylesheet.new(:ipadvertical) do
  import :ipad
  style :ok_button,
    width: 80
end
Teacup::Stylesheet[:ipadvertical].query(:ok_button)
# => {title: "OK!", width: 80}

Direct Known Subclasses

Appearance

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from StylesheetExtension

#app_size, #autoresize, #constrain, #constrain_above, #constrain_below, #constrain_bottom, #constrain_center_x, #constrain_center_y, #constrain_height, #constrain_left, #constrain_right, #constrain_size, #constrain_to_left, #constrain_to_right, #constrain_top, #constrain_width, #constrain_xy, #device, #device_is?, #flexible_bottom, #flexible_height, #flexible_left, #flexible_right, #flexible_top, #flexible_width, #flip, #iPad, #iPadRetina, #iPhone, #iPhone35, #iPhone4, #iPhone5, #iPhoneRetina, #identity, #pi, #rotate, #screen_size, #spin, #transform_layer, #transform_view, #twist

Constructor Details

#initialize(name = nil, &block) ⇒ Stylesheet

Create a new Stylesheet.

If a name is provided then a new constant will be created using that name.

Examples:

Teacup::Stylesheet.new(:ipadvertical) do
  import :ipadbase
  style :continue_button,
     top: 50
end

Teacup::Stylesheet[:ipadvertical].query(:continue_button)
# => {top: 50}

Parameters:

  • name, —

    The (optional) name to give.

  • &block, —

    The body of the Stylesheet instance_eval’d.



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# File 'lib/teacup/stylesheet.rb', line 105

def initialize(name=nil, &block)
  if name
    @name = name.to_sym
    if Teacup::Stylesheet[@name]
      NSLog("TEACUP WARNING: A stylesheet with the name #{@name.inspect} has already been created.")
    end
    Teacup::Stylesheet[@name] = self
  end

  # we just store the block for now, because some classes are not "ready"
  # for instance, calling `UIFont.systemFontOfSize()` will cause the
  # application to crash.  We will lazily-load this block in `query`, and
  # then set it to nil.
  @block = block
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(stylename, &styles) ⇒ Object

supports the ‘new-style’ stylesheet syntax.



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# File 'lib/teacup/stylesheet.rb', line 327

def method_missing(stylename, &styles)
  properties = Limelight.new(&styles).styles
  style(stylename, properties)
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/teacup/stylesheet.rb', line 70

def name
  @name
end

Class Method Details

.[](name) ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 78

def [] name
  stylesheets[name]
end

.[]=(name, stylesheet) ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 82

def []= name, stylesheet
  stylesheets[name] = stylesheet
end

.stylesheets ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 74

def stylesheets
  @stylesheets ||= {}
end

Instance Method Details

#exclude_instance_vars ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 312

def exclude_instance_vars
  @exclude_instance_vars ||= [:@name, :@block, :@imported, :@styles, :@stylesheet_cache]
end

#extends_style?(stylename, extended_name, checked = []) ⇒ Boolean

In the [rare] case you need to know whether the style extends another style, this method will find out quickly. This is mostly useful in the ‘UIView#viewWithStylename` method.

Returns:

  • (Boolean) 


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# File 'lib/teacup/stylesheet.rb', line 291

def extends_style?(stylename, extended_name, checked=[])
  return true if stylename == extended_name

  extended_style_names = styles[stylename][:extends]
  return false unless extended_style_names

  extended_style_names = [extended_style_names] unless extended_style_names.is_a? Array
  return true if extended_style_names.any? { |name| name == extended_name }
  retval = false
  extended_style_names.each do |recusive_check|
    next if checked.include?(recusive_check)

    checked << recusive_check
    if extends_style?(recusive_check, extended_name, checked)
      retval = true
      break
    end
  end
  return retval
end

#get_stylesheet_cache(stylename, target_class, orientation) ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 138

def get_stylesheet_cache(stylename, target_class, orientation)
  self.stylesheet_cache[stylename][target_class][orientation]
end

#import(name_or_stylesheet) ⇒ Object

Include another Stylesheet into this one, the rules defined within it will have lower precedence than those defined here in the case that they share the same keys.

When defining a stylesheet declaratively, it is better to use the symbol that represents a stylesheet, as the constant may not be defined yet:

If you are using anonymous stylesheets however, then it will be necessary to pass an actual stylesheet object.

Examples:

Teacup::Stylesheet.new(:ipadvertical) do
  import :ipadbase
  import :verticaltweaks
end
@stylesheet.import(base_stylesheet)

Parameters:

  • Symbol|Teacup::Stylesheet —

    the name of the stylesheet, or the stylesheet to include.



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# File 'lib/teacup/stylesheet.rb', line 169

def import(name_or_stylesheet)
  @stylesheet_cache = nil
  imported << name_or_stylesheet

  sheet = nil
  if name_or_stylesheet.is_a? Teacup::Stylesheet
    sheet = name_or_stylesheet
  elsif Teacup::Stylesheet.stylesheets.has_key? name_or_stylesheet
    sheet = Teacup::Stylesheet.stylesheets[name_or_stylesheet]
  end

  if sheet
    import_instance_vars(sheet)
  end
end

#import_instance_vars(from_stylesheet) ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 316

def import_instance_vars(from_stylesheet)
  from_stylesheet.run_block

  from_stylesheet.instance_variables.each do |var|
    next if exclude_instance_vars.include? var
    self.instance_variable_set(var, from_stylesheet.instance_variable_get(var))
  end
end

#imported_stylesheets ⇒ Object

The array of Stylesheets that have been imported into this one.



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# File 'lib/teacup/stylesheet.rb', line 274

def imported_stylesheets
  imported.map do |name_or_stylesheet|
    if name_or_stylesheet.is_a? Teacup::Stylesheet
      sheet = name_or_stylesheet
    elsif Teacup::Stylesheet.stylesheets.has_key? name_or_stylesheet
      sheet = Teacup::Stylesheet.stylesheets[name_or_stylesheet]
    else
      raise "Teacup tried to import Stylesheet #{name_or_stylesheet.inspect} into Stylesheet[#{self.name.inspect}], but it didn't exist"
    end

    sheet
  end
end

#inspect ⇒ Object

A unique and hopefully meaningful description of this Object.

Returns:

  • String



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# File 'lib/teacup/stylesheet.rb', line 267

def inspect
  "#{self.class.name}[#{name.inspect}] = #{styles.inspect}"
end

#query(stylename, target_class = nil, orientation = nil, seen = {}) ⇒ Object

Get the properties defined for the given stylename, in this Stylesheet and all those that have been imported.

The Style class handles precedence rules, and extending via ‘:extends` and `import`. If needs the orientation in order to merge and remove the appropriate orientation styles.

Examples:

Teacup::Stylesheet[:ipadbase].query(:continue_button)
# => {backgroundImage: UIImage.imageNamed("big_red_shiny_button"), title: "Continue!", top: 50}

Parameters:

  • Symbol —

    stylename, the stylename to look up.



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# File 'lib/teacup/stylesheet.rb', line 213

def query(stylename, target_class=nil, orientation=nil, seen={})
  return {} if seen[self]
  return {} unless stylename

  cached = get_stylesheet_cache(stylename, target_class, orientation)
  if cached
    # mutable hashes could mess with our cache, so return a duplicate
    return cached.dup
  else
    run_block
    seen[self] = true

    built = styles[stylename].build(target_class, orientation, seen)
    set_stylesheet_cache(stylename, target_class, orientation, built)
    return built.dup
  end
end

#run_block ⇒ Object

the block handed to Stylesheet#new is not run immediately - it is run the first time the stylesheet is queried. This fixes bugs related to some resources (fonts) not available when the application is first started. The downside is that @instance variables and variables that should be closed over are not.

Returns:

  • true if the block was run. false otherwise



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# File 'lib/teacup/stylesheet.rb', line 192

def run_block
  if @block
    _block = @block
    @block = nil
    instance_eval &_block
    true
  end
end

#set_stylesheet_cache(stylename, target_class, orientation, value) ⇒ Object 



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# File 'lib/teacup/stylesheet.rb', line 142

def set_stylesheet_cache(stylename, target_class, orientation, value)
  self.stylesheet_cache[stylename][target_class][orientation] = value
end

#style(*queries) ⇒ Object

Add a set of properties for a given stylename or multiple stylenames.

Examples:

Teacup::Stylesheet.new(:ipadbase) do
  style :pretty_button,
    backgroundImage: UIImage.imageNamed("big_red_shiny_button")

  style :continue_button, extends: :pretty_button,
    title: "Continue!",
    top: 50
end

Parameters:

  • Symbol, —

    *stylename

  • Hash (Symbol, Object) —

    , properties



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# File 'lib/teacup/stylesheet.rb', line 245

def style(*queries)
  if queries[-1].is_a? Hash
    properties = queries.pop
  else
    # empty style declarations are allowed, but accomplish nothing.
    return
  end

  queries.each do |stylename|

    # reset the stylesheet_cache for this stylename
    @stylesheet_cache.delete(stylename) if @stylesheet_cache

    # merge into styles[stylename] (an instance of Teacup::Style). new
    # properties "win" over existing properties.
    Teacup::merge_defaults(properties, styles[stylename], styles[stylename])
  end
end

#stylesheet_cache ⇒ Object

The stylesheet_cache stores “compiled” styles. It is reset whenever the stylesheet imports a new Stylesheet, and when a style entry is added or changed (then only that entry is removed)

This method builds the gnarly hash that stores this stuff - the get/set methods use this method to ensure the object exists, in other places the or the entire cache)



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# File 'lib/teacup/stylesheet.rb', line 129

def stylesheet_cache
  @stylesheet_cache ||= Hash.new do |by_stylename,_stylename|
    by_stylename[_stylename] = Hash.new do |by_target_class,_target_class|
      by_orientation = {}
      by_target_class[_target_class] = by_orientation
    end
  end
end